Lunar and Planetary Institute






SPICEs Program for Fractional and Equilibrium Crystallization Calculations

Oxygen unitsThe modeling codes MAGFOX (Longhi, 1991), MAGPOX (Longhi, 1992), and FXMOTR (a modified version of FXMO and BATCH; Longhi, 2006) were developed in the early 1990s by experimental and lunar petrologist John Longhi to examine magma as it evolved via fractional or equilibrium crystallization. These were written using the FORTRAN programming language. The versions of MAGFOX, MAGPOX, and FXMOTR, available here, have been translated into the MATLAB programming environment by Jesse Davenport (Centre de Recherches Petrographiques et Geochimiques), Clive Neal and Diogo Bolster (University of Notre Dame), Brad Jolliff (University of Washington St. Louis), and John Longhi (Lamont-Doherty Earth Observatory). The new suite of programs is being called Simulating Planetary Igneous Crystallization Environments or SPICEs.

MAGFOX uses Rayleigh fractional crystallization and MAGPOX equilibrium crystallization — both in 1% crystallization steps — to calculate the major element oxide evolution of the liquid and mineralogy using experimentally derived equations and algorithms for liquidus boundaries in several projections (e.g., the Olivine-Plagioclase-Wollastonite-Silica or Ol-Pl-Wo-Sil system) that can be used to derive the crystallization sequence for different magma compositions.  FXMOTR uses a combination of equilibrium and fractional crystallization in 1% crystallization steps to calculate the evolution of major and trace elements of the liquid and the crystallizing mineralogy of magma using equations and algorithms derived from experimental petrology for liquidus boundaries in several projections.

The heritage of these programs is important.  The FORTRAN versions of MAGFOX and MAGPOX, combined with geochemical and petrographic techniques, have been used repeatedly in the past to study lunar igneous suites and their implications for the evolution of the Moon (e.g., magma ocean crystallization, development of the lunar highlands, and the mare basalt source regions).  They have also been used to study igneous suites on the Earth and other terrestrial planetary bodies where olivine is initially on the liquidus.

The new format for MAGFOX, MAGPOX and FXMOTR provides a graphical interface that users with little or no programming experience can harness to model crystallization processes.   This user-friendly code, when combined with geochemical analyses, should provide the phase relationships needed to better understand the petrogenesis of many igneous suites.

Further information and examples of these programs' utility can be found in Davenport et al. (2013). A link to this article will be provided once as soon as possible. Please contact Jesse Davenport (jessedvnprt@gmail.com) or Clive Neal (neal.1@nd.edu) with further questions or comments.

References:

Davenport, J.D., Longhi, J., Neal, C.R., Jolliff, B.L., Bolster, D., 2013. MAGFOX, MAGPOX and FXMOTR: A suite of lunar and planetary igneous crystallization programs. Submitted to Computers and Geosciences, September 2013.

Longhi, J., 1991. Comparative liquidus equilibria of hypersthene-normative basalts at low pressure. American Mineralogist 76, 785–800.

Longhi, J., 1992. Origin of green glass magmas by polybaric fractional fusion. Proceedings of the 22nd  Lunar Planetary Science Conference, 343–353.

Longhi, J., 2006. Petrogenesis of picritic mare magmas: Constraints on the extent of early lunar differentation. Geochimica et Cosmochimica Acta 70, 5919–5934.


 

 

Lunar Magma Ocean